hi, could someone point me to some basics in understanding of video signal. i need to analyze a video input signal very roughly, like brightness/luminosity of black/white in low resolution an framerate (some frames per second). actually i want to detect changes or movement through the picture/screen. i have installed gem and pdp, but don't know all the objects yet. later it is also important, that i will be able to run the patch in -nogui mode, because the cpu is quite old and slow and i need all available resources. i think Gem is not working then??? hardware is working fine (though slow, 200MHz, for video input i use a win-tv card), only my "know how" is poor : ( btw some objects of pdp cannot be created (pdp_blur, pdp_motion_phase). should i change to a newer version? now i am using 0.10.1. and last question: pdp_xv shows an error: no xv port available. is this a software problem, or does my tv-card not support this?
thnx in advance, marius.
On Sun, 23 Mar 2003, marius schebella wrote:
i need to analyze a video input signal very roughly, like brightness/luminosity of black/white in low resolution an framerate (some frames per second). actually i want to detect changes or movement through the picture/screen.
I made a very simple brightness analyzer for PDP a couple of days ago. It outputs the average of the red, green and blue components as fkoats in each frame. Haven't published it yet, because it was a quick and dirty hack on a late night. I expect to rush it out in a couple of days...
btw some objects of pdp cannot be created (pdp_blur, pdp_motion_phase). should i change to a newer version? now i am using 0.10.1.
Add the abstractions directory of PDP to your pd -path ... (best done in your ~/.pdrc file).
and last question: pdp_xv shows an error: no xv port available. is this a software problem, or does my tv-card not support this?
XV is an extension to X, and has nothing to do with your tv card. Check your XFree86 configuration.
best, j#|@
hi..
gem's video analysis objects: pix_blob the weight (size) of a colour in an image stream.. pix_histo output the RGBA density of a stream to a table.. pix_dump output RGBA values of a frame as a list.. pix_pix2sig~ convert RBBA channels to audio signals.. used in combination with: pix_threshold threshold filter.. rgb2hsv convert RGB values to HSV colourspace.. may get you somewhere.. pix_dump is particularly useful for analysis as you can interpret each frame anyway you like, i used it in combination with the matrix objects from the zexy library, but beware it can be processor intensive.. there are probably many more analysis objects in the gem CVS?
pdp has no analysis objects as such, but yves' pidip extention
has a couple:
pdp_ctrack colour tracker, outputs the coordinates of a
colour(+luminosity) in a video stream..
pdp_mgrid outputs cell coordinates of a grid where motion
is detected..
and of course there's yves' pdp2gem/gem2pdp bridge objects for the best of both worlds..
if you don't have Xfree 4.x, then you won't have xv output, either upgrade X or download the sdl library, recompile pdp and use pdp_sdl for pdp output.
enjoy! dmotd
On Sun, Mar 23, 2003 at 04:15:48PM +0100, marius schebella wrote:
hi, could someone point me to some basics in understanding of video signal. i need to analyze a video input signal very roughly, like brightness/luminosity of black/white in low resolution an framerate (some frames per second). actually i want to detect changes or movement through the picture/screen. i have installed gem and pdp, but don't know all the objects yet. later it is also important, that i will be able to run the patch in -nogui mode, because the cpu is quite old and slow and i need all available resources. i think Gem is not working then??? hardware is working fine (though slow, 200MHz, for video input i use a win-tv card), only my "know how" is poor : ( btw some objects of pdp cannot be created (pdp_blur, pdp_motion_phase). should i change to a newer version? now i am using 0.10.1. and last question: pdp_xv shows an error: no xv port available. is this a software problem, or does my tv-card not support this?
thnx in advance, marius.
PD-list mailing list PD-list@iem.kug.ac.at http://iem.kug.ac.at/cgi-bin/mailman/listinfo/pd-list
pdp has no analysis objects as such, but yves' pidip extention has a couple: pdp_ctrack colour tracker, outputs the coordinates of a colour(+luminosity) in a video stream.. pdp_mgrid outputs cell coordinates of a grid where motion is detected..
just a hint:
there is a "workaround" to analyze pictures by using pdp_scanxy~ this object works like tabplay~, but it scans the luminocity channel of a video frame, instead of an array. it accepts coordinates as signal input. (0,0) is top left and (1,1) is bottom right. you could use a phasor~ object to generate coordinates.
if you use the audio output of pdp_scanxy~ in combination with env~ and some lop~ and hip~ objects, you can construct some very basic motion (hip) and intensity (lop) detection objects.
tom
hi, thanks a lot for all the suggestions on video analysis!!! i use now glx for output, (need it for debugging and building only, during performance i do not need it, ... i still was not able to install xvideo...) and pdp_scanxy~ for analyzing the picture. with pdp_v4l is it possible to have a smaller resolution than 64*64? or is then the input messed up? 4*4 or 5*5 would be enough for my purposes. and i cannot switch to greyscale with the command "type grey". pdp gives an error message like "no method for 'type'". but these are subtleties. in the main the patch is working. marius.
----- Original Message ----- From: "Tom Schouten" doelie@zzz.kotnet.org To: "dmotd" dmotd@zapz.net Cc: pd-list@iem.kug.ac.at Sent: Monday, March 24, 2003 1:32 AM Subject: Re: [PD] video analysis II
pdp has no analysis objects as such, but yves' pidip extention has a couple: pdp_ctrack colour tracker, outputs the coordinates of a colour(+luminosity) in a video stream.. pdp_mgrid outputs cell coordinates of a grid where motion is detected..
just a hint:
there is a "workaround" to analyze pictures by using pdp_scanxy~ this object works like tabplay~, but it scans the luminocity channel of a video frame, instead of an array. it accepts coordinates as signal input. (0,0) is top left and (1,1) is bottom right. you could use a phasor~ object to generate coordinates.
if you use the audio output of pdp_scanxy~ in combination with env~ and some lop~ and hip~ objects, you can construct some very basic motion (hip) and intensity (lop) detection objects.
tom
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Tom Schouten